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[IEEE TENCON 2019 - 2019 IEEE Region 10 Conference (TENCON) - Kochi, India (2019.10.17-2019.10.20)] TENCON 2019 - 2019 IEEE Region 10 Conference (TENCON) - Point-of-care functional and molecular imaging using LED-based photoacoustics
摘要： Photoacoustic (PA) or optoacoustic imaging can visualize tissue-optical absorbers, especially hemoglobin, with optical contrast and ultrasound (US)-like resolution and imaging depth. Since both PA and US imaging involves US detection, it is straightforward to develop dual-mode imaging systems with unprecedented functional and structural imaging capabilities. Researchers have already demonstrated the potential of utilizing this complementary contrast imaging for several animal imaging experiments and early clinical pilot studies. PA conventionally uses slow, bulky and high-priced lasers as excitation sources. Use of these high-power pulsed lasers is hindering the clinical translation process of this imaging modality with tremendous potential. Advances in solid-state device technology have recently resulted in the development of a new class of high-power light emitting diodes (LEDs) that can be used as fast, robust and affordable pulsed excitation sources for PA imaging. In this paper, we review multiple LED-based PA/US imaging implementations (commercial and lab-made systems) and demonstrate its functional, molecular and structural imaging capabilities using several clinical/preclinical imaging examples. Specific focus will be given to 2D and 3D superficial vasculature and oxygen saturation imaging in multiple in vivo clinical and preclinical studies.
关键词： ultrasonography,vasculature,photoacoustic imaging,oxygenation imaging,LED
更新于2025-09-16 10:30:52
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Intra-cavity multi-point sensor for C2H2 detection in photoacoustic spectroscopy based on acousto-optic Q-switched fiber laser
摘要： In this paper, we reported a new multi-point sensor for C2H2 detection based on photoacoustic spectroscopy and acousto-optic Q-switched fiber laser. Three transmission-type PAS cells were placed inside the fiber laser cavity and used for C2H2 detection simultaneously to demonstrate the potential of spatially resolved measurements. A maximum pulse peak power of ~544 mW was generated by the acousto-optic Q-switched fiber laser. The signal-to-noise ratios (SNR) calculated from the experimental results was 57.7 dB, 45.1 dB and 57.2 dB. This resulted in a minimum detection limit (MDL) for C2H2 of 1.73 ppmv, 7.82 ppmv and 1.93 ppmv for PAS cell 1, PAS cell 2 and PAS cell 3, respectively.
关键词： multi-point sensor,photoacoustic spectroscopy,fiber laser
更新于2025-09-16 10:30:52
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Preparation of silicon naphthalocyanine nanoparticles by laser ablation in liquid and their optical properties
摘要： Silicon naphthalocyanine nanoparticles were successfully prepared by laser ablation in liquid. Silicon 2,3-naphthalocyanine bis(trihexylsilyloxide) powders in deionized water were irradiated with nanosecond-pulsed laser (Nd:YAG, SHG) to prepare nanoparticles. The prepared nanoparticles were investigated by scanning electron microscopy, dynamic light scattering and spectrophotometry. The shape was polygonal and partially spherical. The primary and secondary particle sizes were reduced with an increase in laser fluence. Absorbance was increased at low laser fluence and was constant at high laser fluence with the increase in laser fluence. The ratio of the two absorbance peaks was changed with the increase in laser fluence.
关键词： optical properties,laser ablation in liquid,nanoparticles,photoacoustic imaging,silicon naphthalocyanine
更新于2025-09-12 10:27:22
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Organic semiconducting polymer amphiphile for near-infrared-II light-triggered phototheranostics
摘要： Development of near-infrared-II (NIR-II) light responsive nano-agents with high photothermal stability, high photothermal conversion efficiency (PCE), and excellent biocompatibility for photoacoustic (PA) imaging-guided photothermal therapy (PTT) is of tremendous significance. In spite of the superiority of organic semiconducting polymer nanoparticles (OSPNs) in PA imaging-guided PTT, the limited absorption in the first NIR (NIR-I) window and metastable nanostructure of OSPNs resulting from commonly used preparation methods based on nanoprecipitation or reprecipitation compromise their in vivo phototheranostic performance. Herein we design and synthesize a novel NIR-II absorbing organic semiconducting polymer amphiphile (OSPA) to enhance the structural stability of OSPNs. With prominent optical properties, low toxicity, and a suitable size, OSPA not only efficiently labels and kills cancer cells under NIR-II irradiation but also accumulates at the tumor of living mice upon intravenous injection, allowing efficient NIR-II light-triggered phototheranostics toward tumor. The developed OSPA has promising potential for fabricating multifunctional nanoplatforms to enable multimodal theranostics.
关键词： second near-infrared window,photoacoustic imaging,semiconducting polymer,amphiphile,photothermal therapy
更新于2025-09-12 10:27:22
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Evaluation of Retinal Pigment Epithelium and Choroidal Neovascularization in Rats Using Laser-Scanning Optical-Resolution Photoacoustic Microscopy
摘要： Purpose: To demonstrate the value of the laser-scanning optical-resolution (LSOR)-photoacoustic (PA) microscopy (PAM) system and the conventional multimodal imaging techniques in the evaluation of laser-induced retinal injury and choroidal neovascularization (CNV) in rats. Methods: Different degrees of retinal injury were induced using laser photocoagulation. We compared the LSOR-PAM system with conventional imaging techniques in evaluating retinal injury with or without CNV. Six additional rats, treated with an anti-VEGF antibody or immunoglobulin G immediately after photocoagulation, were imaged 7 and 14 days after injection, and CNV lesion areas were compared. Results: In the retinal injury model, fundus autofluorescence showed well-defined hyperreflection, while the lesion displayed abundant PA signals demonstrating nonuniform melanin distribution in retinal pigment epithelium (RPE). RPE was detected with higher contrast in the PAM B-scan image than optical coherence tomography (OCT). Additionally, the CNV lesion was present with multiple PA signal intensi- ties which distinctly characterized the location and area of CNV as found in fundus fluorescein angiography. Further- more, the decreased PA signals extending from the CNV le- sion were similar to those of the vascular bud in ex vivo im- aging, which was invisible in other in vivo images. When treated with anti-VEGF agents, statistically significant differ- ences can be demonstrated by PAM similar to other mo- dalities. Conclusions: LSOR-PAM can detect the melanin distribution of RPE in laser-induced retinal injury and CNV in rats. PAM imaging provides a potential new tool to evalu- ate the vitality and functionality of RPE in vivo as well as to monitor the development and treatment of CNV.
关键词： Age-related macular degeneration,Retinal pigment epithelium,Multimodal imaging,Photoacoustic microscopy,Choroidal neovascularization
更新于2025-09-12 10:27:22
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[IEEE 2019 Conference on Lasers and Electro-Optics Europe & European Quantum Electronics Conference (CLEO/Europe-EQEC) - Munich, Germany (2019.6.23-2019.6.27)] 2019 Conference on Lasers and Electro-Optics Europe & European Quantum Electronics Conference (CLEO/Europe-EQEC) - Optical Frequency Comb Photoacoustic Spectroscopy
摘要： Photoacoustic spectroscopy (PAS) based on continuous wave (cw) lasers provides high absorption sensitivity in small sample volume [1, 2] but it is usually restricted to single species detection because of the limited tunability of cw lasers. Broadband PAS has been demonstrated using cantilever-enhanced detectors in combination with incoherent [3] or supercontinuum [4] light sources modulated by conventional Fourier transform spectrometers (FTS), however, the spectral resolution was limited to a few cm-1. Here we report the first demonstration of optical frequency comb photoacoustic spectroscopy (OFC-PAS), which combines the wide spectral coverage and high resolution of frequency combs with the small sample volume of photoacoustic detection [5]. The OFC-PAS setup is based on a doubly-resonant optical parametric oscillator pumped by a femtosecond Tm:fiber laser with a repetition rate of 125 MHz. The intensity of the signal output centered at 3.3 μm is modulated at ~500 Hz using an FTS. One output of the FTS (4.8 mW of signal power) is directed to a 10-cm-long cantilever-enhanced photoacoustic cell with 8 mL volume (Gasera, PA201), while the other is measured with a photodetector and used for normalization of the PA spectrum. Figure 1(a) shows in red the room temperature OFC-PAS spectrum of the C-H stretch band of 100 ppm of CH4 in N2 at 1000 mbar and 1 GHz resolution (left axis) recorded in 200 s (no averaging). The blue curve shows the simulated absorption coefficient, (cid:68), based on the parameters from the HITRAN database (right axis). A zoom-in around the Q-branch region at 1000 mbar and 400 mbar is shown in Figs 1(b) and 1(c), demonstrating the high spectral resolution, no instrumental lineshape distortion, and good agreement with the simulation. The limit of detection (LOD), evaluated from the signal to noise ratio of the methane line at 3058 cm-1 at 1000 mbar, is 0.8 ppm in 200 s for power spectral density of 42 μW/cm-1. While this LOD is comparable to those obtained with other broadband PAS methods [3, 4], the resolution of OFC-PAS is more than two orders of magnitude better. The normalized noise equivalent absorption at 1000 mbar is 8 × 10-10 W cm-1 Hz -1/2, comparable to values reported with PAS based on cw lasers [2]. OFC-PAS thus extends the capability of optical sensors for high-resolution multicomponent trace gas analysis in small sample volumes.
关键词： high-resolution spectroscopy,optical frequency comb,trace gas analysis,Photoacoustic spectroscopy
更新于2025-09-12 10:27:22
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Fully Coupled Model for Frequency Response Simulation of Miniaturized Cantilever-Based Photoacoustic Gas Sensors
摘要： To support the development of miniaturized photoacoustic gas sensors, a fully coupled ?nite element model for a frequency response simulation of cantilever-based photoacoustic gas sensors is introduced in this paper. The model covers the whole photoacoustic process from radiation absorption to pressure transducer vibration, and considers viscous damping loss. After validation with experimental data, the model was further applied to evaluate the possibility of further optimization and miniaturization of a previously reported sensor design.
关键词： photoacoustic spectroscopy,sensor miniaturization,viscous damping,COMSOL
更新于2025-09-12 10:27:22
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Fixed-Path Length Laser-Induced Sound Pinging: A Streamlined Method for Sound Speed Determination in Arbitrary Liquids
摘要： Recently, we introduced laser-induced sound pinging (LISP) as a simple photoacoustic technique for the expedient and fairly rapid (2?3 min) measurement of the speed of sound traversing low-volume samples (25?1000 μL), built around an inexpensive tattoo-removal source (Sens. Actuators B-Chem. 2019, 291, 401?410). In this report, we expand on the utility of this technique by improving the facility of measurement and speed of analysis by adopting a ?xed-path length (FPL) architecture which allows for much faster analysis (1?5 s) of similar sample volumes. The FPL-LISP setup was employed to determine the speeds of sound at temperatures from 293 to 333 K for four popular hydrophilic deep eutectic solvents (DESs) containing choline chloride (i.e., reline, ethaline, glyceline, and maline), plus several representative decanoic acid?based (i.e., hydrophobic) DESs. The temperature-dependent speeds of sound were used alongside the corresponding experimental densities to calculate the bulk modulus for these illustrative DESs. Interestingly, the bulk modulus was in the 4000?5000 MPa range for choline chloride-derived DESs, essentially twice the value of a hydrophobic DES (typi?ed by 1:2 tetraoctylammonium bromide/decanoic acid), suggesting unique potential for hydraulic applications, for example. The modest volume requirements of FPL-LISP make it suitable for determining the speed of sound in scarce, precious, or hazardous liquids, and the speed of analysis enables integration into a continuous-?ow platform for real-time analytics (e.g., beverage quality control).
关键词： bulk modulus,speed of sound,laser-induced sound pinging,photoacoustic technique,deep eutectic solvents
更新于2025-09-12 10:27:22
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Midinfrared Light-Emitting Diodes Based on А3В5 Heterostructures in Gas-Analyzer-Equipment Engineering: Potential and Applications in 2014–2018
摘要： Studies published in the period from 2014 to 2018 that are aimed at creating nondispersive and photoacoustic IR gas analyzers with LED radiation sources based on А3В5 heterostructures and operating in a range of wavelengths from 3 to 5 μ m are reviewed. Potential of gas analysis equipment based on the aforementioned LEDs for detecting CO, CO2, methane, and other gases is analyzed.
关键词： photoacoustic gas analyzer,nondispersive gas analyzer
更新于2025-09-12 10:27:22
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Micro‐CT study on the removal of accumulated hard‐tissue debris from the root canal system of mandibular molars when using a novel laser‐activated irrigation approach
摘要： Aim To compare the efficacy of ultrasonically activated irrigation (UAI), photon-induced photoacoustic streaming (PIPS), and shock wave enhanced emission photoacoustic streaming (SWEEPS) activation for the removal of accumulated hard-tissue debris (AHTD) from the root canal system of mandibular molars when assessed using microcomputed tomography (micro-CT). Methodology A total of 30 mandibular first and second molars with joining mesial root canals containing an isthmus and a single distal canal were subjected to three micro-CT scans (before and after canal instrumentation and after final irrigation) at a resolution of 15 μm. Mesial canals were prepared up to Protaper F3 rotary file, and distal canals were prepared up to Protaper F4 rotary file. Teeth were randomly assigned to 3 groups according to the irrigant activation method (n = 10): the UAI group, the PIPS group, and the SWEEPS group. The final irrigation procedures were performed using a total of 15.5 mL of 1% NaOCl for each tooth with an activation time of 3 × 30 s. After three-dimensional model reconstruction and volumetric measurement of root canals, the percentage reduction (%Rd) of AHTD was calculated. The %Rd of AHTD was analyzed statistically using one-way analysis of variance and nonparametric tests at a significance level of 5%. Results There were no significant differences between the three groups in terms of canal volume before or after instrumentation, or the volume of debris after canal preparation (P > 0.05). In the mesial canals, irrigation with SWEEPS reduced the overall debris by 84.31%, which was significantly more than the reduction associated with PIPS and UAI (58.79% and 50.27%, respectively). In the distal canals, the %Rd of AHTD was significantly different between PIPS and SWEEPS and between UAI and SWEEPS (P < 0.05), but was not significantly different between PIPS and UAI groups (P > 0.05). The SWEEPS had higher %Rd of AHTD than the PIPS and UAI groups. Conclusions SWEEPS was associated with significantly less debris compared than PIPS and UAI, especially in isthmus-containing mesial roots. None of the activation techniques completely removed debris from root canal systems.
关键词： ultrasonic,photoacoustic streaming,irrigation,hard-tissue debris
更新于2025-09-12 10:27:22